Card static tester



June 26, 1962 R. A. CRANE 3,041,531

cm: STATIC TESTER Filed Au 24, 1959 INVENTOI? ME I. OFF/V6 ATTORNEYS its This invention relates to static testers and particularly to a card static tester which is provided with a pair of small carding rolls for simulating actual static conditions in fiber carding operations and which is provided with means for measuring the static field which results from such operations.

The processing of textile fibers and fabrics often produces charges of static electricity on the materials which may result in rather uncomfortable conditions for operating personnel and also interfere with the proper processing of the materials. Highly electrostatically charged textile fibers tend to fiy off processing machinery, and low or intermediately charged Webs of fibers tend to balloon and to be attracted to grounded metal surfaces as they are transferred from place to place. All of these conditions interfere with the proper operation of a textile plant and require that some precautions be taken to eliminate or minimize the effects of the static charges. It has, therefore, become very important that the intensity of the electric charges on fibers which are being processed should be determinable with a reasonable degree of accuracy, under various ambient conditions.

Carding of fibers is especially productive of undesirable electrostatic charges, so that it is desirable to be able to predetermine the intensity of such static charges resulting from the carding of various fibers in order to assist in determining corrective measures which should be taken to minimize their effects. It has been found that the control of electrostatic charges generated during the treatment of natural and regenerated cellulose and protein fibers can generally be overcome by raising the humidity in a mill to provide for natural leakage or discharge of the static charge. Synthetic hydrophobic fibers, however, require the use of special chemical agents for the effective control of undesirable static charges due in part to their water repellant characteristic.

According to the present invention, a miniature carding machine is provided which reproduces actual conditions and is provided with a static field measuring device for conveniently determining the charge generated by the fiber being tested. This equipment comprises a pair of small carding rolls having a number of wire combing bristles arranged over the surface of each of the rolls. These bristles extend generally outwardly of the rolls, and the rolls are rotatably mounted with their axes substantially parallel and spaced apart so that the ends of the combing bristles on adjacent surfaces of the two rolls are very closely spaced. Suitable drives are provided for each of the rolls and are controllable so that either of the rolls may be made to rotate faster than the other, thus providing for the transfer of fibers from either roll to the other. A suitable meter or oscilloscope is provided for measuring the electrostatic charge which may be developed upon fibers placed on and combed by the carding rolls.

The equipment preferably also is provided with a safety circuit which is arranged and connected in the control system of the device in such a manner that if an operator accidentally should place his fingers or hand in a position under a carding roll so that hemight be injured, the circuit is immediately opened, and the carding rolls are mechanically disconnected from their driving equipment to stop them substantially instantly. The safety circuit also preferably includes a holding circuit arrangeaet ment for maintaining the system deenergized after it has been brought to a stop in order to enable the operator to remove his hand or fingers from the position dangerously close to the carding rolls without having the equipment restarted. A simple resetting circuit is provided for deenergizing this holding circuit and restoring the system to its normal control and operating conditions.

An object of the present invention is to provide an improved static tester.

Another object of this invention is to provide an improved and simplified card static tester which simulates actual fiber carding operations.

A further object of this invention is to provide an improved static tester having a maximum safety for the operating personnel.

Further objects and advantages of this invention will become apparent from the following description referring to the accompanying drawing, and the features of novelty which characterize this invention will be pointed outwith particularity in the claims appended to and forming a part of this specification.

In the drawing:

FIG. 1 is a schematic diagram illustrating the mechanical and electrical parts of an improved static tester embodying the present invention; and

FIG. 2 is a fragmentary view of the end of one of the carding rolls utilized in the static tester shown in FIG. 1.

Referring to the drawing, an improved static tester embodying the present invention is illustrated. This tester is provided with a pair of small carding rolls 10 and 1 1, which are adapted to be operated as a miniature fiber carding machine. The carding rolls 10 and 11 are provided with central drums 10' and 11 mounted respectively on drive shafts 12 and 13. These carding rolls are formed with a plurality of wire combing bristles 14 which extend generally outwardly from the surfaces thereof for holding and combing fibers whichare placed on the rolls. In order accurately to simulate actual carding of fibers the combing bristles 14 are curved or bent so that they extend slightly in the normal direction of rotation of each respective roll. This preferably is obtained by bending each bristle at about half Way of its length at an angle of approximately thirty degrees from radial in the direction of normal rotation of the roll, as shown in detail in FIG. 2. The two rolls are rotatably mounted on any suitable support 15 so as to position the axes of the rolls substantially parallel and with the bristles on adjacent sides of the rolls spaced in closely adjacent relationship.

The two carding rolls .are adapted to be driven in opposite directions, as indicated by the arrows in FIG. 1, and provision is made for driving the rolls at the same or at diiferent speeds and for quickly changing the speed relationship of the two rolls, so that the higher speed roll may quickly be made to operate as the lower speed roll and vice versa. The carding rolls 10' and 11 are adapted to be driven by suitable electric motors 16 and 17 through motor drive shafts 16 and 17 and suitable clutches 18 and .19, respectively. The driving motors 16 and 17 are adapted to be energized from a common source of electrical power supply for the entire static tester through conductors 20 and 21 and a main circuit breaker having contacts 22 and 23. One side of each of the motors 16 and 17 is connected to a common line 24, which is electrically connected to the main circuit breaker contacts 23 through a set of contacts 25 and a contactor 26 of a holding relay 27. The other terminals of the motors 16 and 17 are connected respectively through conductors 28 and 29 to contacts 30, and 31 and 31' of a two-way switch. This two-way switch is provided with contactors 32 and 32 which are, respectively, connected to a terminal 33 and a variable contactor 33' line 20 through the variable contact 33'. L for energization of the motor 17 at a higher voltage than of a suitable voltage varying device 34, such as a variable resistance or an adjustable transformer. This voltage varying device is adapted to be connected to the other side of the electrical power supply through the contacts 22 of the main circuit breaker.

This circuit provides for driving both carding rolls at the same speed by energizing their respective driving motors 16 and 17 with the two-way switch contactors 32 and 32 thrown in either direction to complete, an electrical circuit through the contact 36 and either of the contacts 31 and 31' when the voltage varying device contact 33' is in the extreme position coinciding with the terminal 33. In actual operation, carding rolls are prac tically never driven at the same speed, as carding or combing of fibers requires that they be transferred from one roll to another, and this is accomplished by driving one roll at a higher speed than the other so that fibers are transferred from the more slowly rotating roll to the higher speed roll.

In the present card static tester, 'a continuous carding of fibers is simulated by alternately driving each of the rolls as the higher speed roll when most of the fibers have been transferred from one roll to the other. In this manner, the same group of fibers can be continuously used and be repeatedly transferred from a slow moving roll to a higher speed roll, thereby simulating the carding of a much larger number of fibers. This can readily be obtained by alternately operating the roll driving motors .16 and 17 as the higher speed motor by alternately energizing one of these motors at a higher voltage than the other. Furthermore, .the relative speeds of operation of the two motors preferably are adjustable in order to.

simulate as nearly as possible different speeds of operation of actual carding rolls. These speed control features are readily attainable in the present static tester throughthe electrical circuit connections of the motors 16 and 17 to the source of electrical power supply.

The desired relative speed of the two motors is readily obtainable by varying the position of the variable contact 33' of the voltage varying device, so that one of the motors is connected directly to the electrical supply line 20 through the voltage varying device terminal 33, while the other motor is connected to this electrical supply line 26 through the variable contact 33and therefore usually is energized at a lower voltage than the other motor, thus being operable at a lower speed than the other motor. Alternate operation of the motors as higher and lower speed motors is readily obtained by the connection of the motors through the two-way switch cont-actors 32 and 32'. As is clearly shown in FIG. 1, when the contactors 32 and 32 close electric circuits through the contacts 30 and 31' the motors 16 and 17 are, respectively, connected to the voltage varying device terminal 33 and variable contact 33'. This impresses a higher volt-age upon the driving motor 16 than upon the driving motor 17, thus resulting in a higher speed of the motor 16 than the motor 17, and a consequent higher speed of the carding roll than the speed of the carding roll 11.

With such an electrical connection, fibers 35 on the carding rolls will be transferred from the bristles 14 on the carding roll 11 to the bristles of the carding roll 10. When substantially all of the fibers have been transferred to the carding roll 10, it may be desired to continue the combing of the fibers in order to obtain a higher measurable static charge on the fiebers so as to simulate a longer carding operation. This can readily be obtained by throwing the contactors 32 and 32' of the two-Way switch to close electric circuits *by these contactors, respectively, through the switch contacts 31 and 30. In this position of the contactors of the two-way switch, the driving motor 17 is connected directly to the electrical supply line through the voltage varying device terminal 33,'while the driving motor 16 is connected to the electrical supply This provides the motor 16, as a consequence of which the motor 17 and, therefore, the carding roll 11 operate at a higher speed than the motor 16 and its carding roll 10. Thus, 'by simply throwing the two-Way switch from one position to another, each carding roll may alternately be driven as the higher speed roll and the fibers 35 consequently be alternately transferred from one roll to the other.

In order to obtain useful information regarding the generation of electrostatic charges generated by the combing or carding of the fibers, it is desirable that the intensity of this charge be readily measurable, and that comparable operating conditions should be maintained in order to provide results which may be analyzed for a practical determination of the static-producing qualities of the fibers undergoing test. This is obtainable by operating the carding rolls at predetermined speeds for either a predetermined period or for a predetermined number of transfers of fibers substantially completely from the lower speed roll to the higher speed roll. Furthermore, the electrostatic voltage measuring instrument should be placed at a predetermined distance from the carding rolls, so that its measurements will be comparable for difierent tests, as it is well known that an electrostatic potential varies with the distance between the measuring instrument and the change under measurement. Any suitable meter, electrometer, or oscilloscope may be used for measuring or indicating the. electrostatic charge upon the I fibers on the carding rolls. -It has been found, however,

that the ambient of the card static tester may seriously affect the measurement of the electrostatic charge on the carded fibers so that consistent results may not be obtained unless provision is made to compensate for various ambient factors including temperature and humidity.

A highly emcient electrostatic field strength measurement may be obtained by an instrument having a probe 36 mounted a fixed or predeterminable distance from the carding rolls within an electrically conductive shielding housing 37 which is formed with an aperature 37 therein adjacent to the probe 36, so that the probe may be exposed to the electrostatic field on fibers 35 on the carding rolls under substantially constant conditions. 'In order further to assure a substantially constant ambient for the field to which the probe 36 is subjected and to correct for ambient variations by minimizing interference with accurate measurements of the electrostatic field by stray fibers, dust, and other foreign materials, a fan 38 preferably is provided, which may be driven at any desired speed from a suitable source of power so as to draw air into the housing 37, as indicated by arrows 38', blow it around the probe 36, and out through the aperture 37'.

Under normal conditions the potential of the probe 36 will become the same as that of the electrostatic field produced by fibers on the carding rolls, and once this potential has been reached no further current will pass from the probe 36 to any measuring or indicating instrument connected to the probe, so that a continuous reading of the amplitude of the electrostatic field is not obtainable unless the probe is continuously charged and discharged by some suitable means. Such a continuous alternately charging and discharging of the probe 36 can readily be obtained by periodically grounding the probe or by arranging a chopper or fan member having blades 39 supported by a hub 39' rotatably mounted within the housing 37, such that rotation of the blades 39 periodically blank out the aperture 37 in the housing and periodically shield the probe 36 from the electrostatic field to which it is subjected when the aperture 37 is unshielded by the spaces between the blades 39.

In order to obtain the desired alternate shielding and opening of the aperture 37', the blades 39 are formed of an electrically conductve material and the chopper hub 39' is mounted on a drive shaft 40, which is adapted to be driven by any suitable source of power, such as an electric motor 4-1. As schematically illustrated in FIG. 1, the chopper blades 39 and the fan 38 may both be driven by the motor 4 1, or separate motors may be provided for driving these two elements, if this be desired. The motor 41 is adapted to be energized independently of the carding roll driving motors 16 and 17 and is adapted to be connected to the source of electrical power supply through the leads 2% and 21 by a suitable circuit breaker 42.

In order to obtain a more accurate electrostatic field measurement and results which are more readily comparable, the probe 36 preferably is connected through a suitable amplifier 43 to any suitable voltage measuring or indicating instrument 44. In this manner, the electrostatic charge generating characteristics of any fibers may be readily determined by placing a predetermined amount of these fibers 35 on the carding rolls It) and 11 and operating these rolls so as to transfer the fibers from one roll to the other, for a predetermined number of times or for a predetermined length of combing or cording of the fibers, at predetermined relative speeds of the carding rolls, and by observing or recording the intensity of the electrostatic field impressed on the probe 36 as measured by the instrument 44-.

This provides for a very efiicient and accurate predetermination of the electrostatic field which is to be expected during normal carding operations, so that proper and eifec-tive measures may be taken for eliminating or minimizing such a field. Furthermore, it provides an arrangement for readily testing the effectiveness of chemicals which may be used for treating the fibers or the ambient of the carding equipment for minimizing or eliminating the generation of electrostatic charges on fibers during a carding thereof. The simple operations for obtaining the desired test results by merely closing three circuit breakers or switches, and observing or recording the magnitude of the electrostatic field, as measured by the the instrument 44, makes it possible to utilize semi-skilled on unskilled personnel for conducting tests with this improved card static tester.

It has been found that operators of a card static tester of the present type occasionally place their hands or fingers under the carding rolls. This may easily result in serious injury, especially since the wire bristles 14- are curved or extend angularly in the direction of rotation of the rolls. It becomes imperative, therefore, that the carding rolls be stopped immediately should a person accidentally place his hands or fingers under such rolls. This can readily be accomplished by placing a safety push-button switch 45 directly under the outer carding roll 10, spaced a slight distance from the ends of the bristles 14, so that the insertion of a persons fingers or hand between the underside of the roll and the push-button switch 45 will cause a depression of the push-button switch and close a safety electrical circuit through this switch.

This safety circuit includes an operating coil 46, for the holding relay 27, connected in series with a normallyclosed reset push-button switch 47, and an energizing circuit for operating coils 48 and 49 of solenoid releases 48 and 49, respectively. Depression of the normallyopen safety push-button switch 45 will connect the solenoid release operating coils 48 and 49 to the source of electrical power supply lines and 21 through the main circuit breaker contacts 22 and 23 and will instantly disengage the carding roll driving clutches '18 and 19, thereby completely disengaging all mechanical connections between the carding rolls and their driving motors. This has the eifect of completely removing all of the rotational inertia of the driving motors and the drive shafts from the carding rolls, thereby permitting these rolls to stop very quickly, so as to minimize the scratching or gouging of the persons fingers or hand which have come in contact with the roll bristles 14 and the button of the safety-button switch 45.

In addition, such a closure of the safety push-button switch 4 5 energizes the operating coil 46 of the holding relay 27 so as to actuate this relay and open the circuit of the carding roll driving motors 16 and 17 through the relay contacts 25, thus deenergizing these motors and bringing them to a standstill. Actuation of the holding relay also closes a circuit through relay contacts 50 and the relay contactor 26, so as to provide a holding circuit around the safety push-button switch 45, which maintains the energization of the holding relay operating coil 46 by the circuit which is close-d through the contacts 50. Thus, if a person should release the pressure upon the safety push-button switch 45 in partially or completely withdrawing his fingers, the solenoid clutch release coils 48 and 49 will remain energized and the clutches 18 and 19 will remain disconnected, while the driving motors l6 and 17 are also maintained in a denergized condition.

Reclosing of the clutches and reenergizing of the carding drive motors can only be obtained by a manual depression or opening of the normally-closed resetting switch 47. Manual opening of the resetting switch 47 will deenergize the operating coil 46 of the holding relay 27 for resetting the safety circuit through the safety relay 27, thereby reclosing the circuits of the driving motors 16 and 17 and opening the circuits of the solenoid clutch release operating coils 4S and 49 and permitting the reclosure of the clutches l8 and 19 to provide for driving the carding rolls l0 and 11 by the motors 16 and 17. This is a very important aspect of this safety feature, for a person who has accidentally placed his fingers or hand between the bristles of the carding roll 10 and the safety switch 45 might other- Wise partially withdraw his fingers or hand sufficiently to release the pressure on the safety switch 45, thereby causing an opening of the switch and a reactuation of the carding rolls, if the driving motors and the clutches are not maintained inoperative until the fingers or hand are completely safely removed. In this manner, an improved card static tester made in accordance with this invention provides a device for accurately, readily, and safely simulating actual fiber carding conditions and comparably measuring the amplitude of electrostatic fields set up by various different types of fibers and variously treated fibers by skilled or unskilled operating personnel.

While a particular embodiment of this invention has been illustrated and described, modifications thereof will occur to those skilled in the art. It is to be understood, therefore, that this invention is not to be limited to the particular arrangement and circuits disclosed and it is intended in the appended claims to cover all modifications within the spirit and scope of this invention.

What is claimed is:

1. A static tester comprising a pair of small carding rolls, each of said rolls having a plurality of wire combing bristles on the surface thereof extending generally outwardly for holding and combing fibers thereon, means for rotatably mounting said rolls with the ends of said bristles of different rolls in closely adjacent relationship, means for selectively alternately driving one of said rolls faster than the other, and means arranged adjacent to said carding rolls for measuring the static electrical potential of fibers carded by said carding roll bristles.

2. A static tester comprising a pair of small carding rolls, each of said rolls having a plurality of wire combing bristles on the surface thereof extending generally outwardly for holding and combing fibers thereon, means for rotatably mounting said rolls with the ends of said bristles of different rolls in closely adjacent relationship, means for driving said rolls, means for selectively alternately driving one of said rolls faster than the other, means for varying the speed of one of said rolls, and means arranged adjacent to said carding rolls for measuring the static electrical potential of fibers carded by said carding roll bristles.

3.. A static tester comprising a pair of carding rolls, each of said rolls having a plurality of wire combing bristles on the surface thereof extending generally outwardly, means for rotatably mounting said rolls with the ends of said bristles of different rolls in closely adjacent relationship, separate means including a motor for driving each of said rolls, means for energizing said motors for operation thereof and said rolls at difierent speeds, means for varying the speed of one of said motors, and means including a periodically grounded probe arranged adjacent to said carding rolls for measuring the static electrical potential of fibers carded by said carding roll bristles,

4. A static tester comprising a pair of carding rolls, each of said rolls having a plurality of wire combing bristles thereon extending generally outwardly and curved in the'normal direction of rotation, means for rotatably mounting said rolls with the ends of said bristles of ditferent rolls in closely adjacent relationship, separate means including a motor for driving each of said rolls,

means for energizing said motors for operation thereof and said rolls at difierent speeds, means for selectively alternately energizing said motors for operation of one alternately at a higher speed than the other for selectively alternately driving one of said carding rolls faster than the other, and means for measuring the static electrical potential of fibers carded by said carding roll bristles,

5. A static tester comprising a pair of small carding rolls, each of said rolls having a plurality of wire combing bristles on the surface thereof extending generally outwardly forholding and combing fibers thereon, means for rotatably mounting said rolls with the ends of. said bristles of diiferent rolls in closely adjacent relationship, eans for driving said rolls, means for selectively alternately driving one of said rolls faster than theother,

means for varying the speed of one of said rolls, means including a clutch for 'providinga driving connection driving connection, a safety circuit for stopping operation of said carding rolls including a circuit breaker having an operating element located under the outer of said rolls arranged to be closed by pressure thereon for energizing said solenoid means for disengaging said clutch means, means responsive to closure of said safety circuit breaker for stopping said driving means, and means including a periodically grounded probe arranged adjacent to said carding rolls for measuring the static electrical potential of fibers carded by said carding roll bristles. v I

6. A static tester comprising a pair of small carding rolls, each of said rolls having a plurality of wire combing bristles on the surface thereof extending generally outwardly, means for rotatably' mounting said rolls with the ends of said bristles of different rolls in closely adjacent relationship, separate means including a motor for driving each of said rolls, means for energizing said motors for operation thereof and said rolls at dilferent speeds, means for varying the speed of one of said motors, means including a clutch for providing a driving connection between each of said motors and its respective driven carding roll, electromagnetic solenoid means for disengaging said solenoid means for disengaging said clutches, means responsive to closure of said safety circuit breaker for deenergizing said carding roll driving motors, and means including a periodically grounded probe arranged adjacent to said carding rolls for measuring the static electrical potential of fibers held and combed by said carding roll bristles.

7. A card static tester comprising a pair of small carding rolls, each of said rolls having a plurality of wire combing bristles extending generally outwardly from said rolls for holding and combing fibers thereon, means for rotatably mounting said rolls with the ends of said bristles of difierent rolls in closely adjacent relationship, means for selectively alternately driving one of said rolls faster than the other and also for varying the speed of one of said rolls, a safety means for stopping operation of said carding rolls including an operating element located under the outer of said rolls arranged to be closed by pressure thereon for disengaging said driving means to said rolls, and means arranged adjacent to said carding rolls for measuring the static electrical potential of fibers combed by said carding roll bristles.

8. A card static tester comprising a pair of carding 'rolls, each of said rolls having a plurality of wire combing bristles thereon extending generally outwardly with substantially the outer half of each bristle extending angularly in the normal direction of rotation about 30 degrees from radial, means for rotatably mounting said rolls with the ends of said bristles of different rolls in closely adjacent relationship, separate means including a motor for driving each of said rolls, means for energizing said motors for operation thereof and said rolls at difierent speeds, means including a clutch for providing a driving connection between each of said motors and its respective driven carding roll, electromagnetic solenoid means for disengaging each of said clutch driving connections, a safety circuit for stopping operation of said carding rolls including a circuit breaker located under the outer of said rolls arranged to be closed by pressure thereon for energizing said solenoid means for disengaging said clutches, means responsive to closure of said safety circuit breaker for deenergizing said carding roll driving motors, a holding circuit for maintaining said latter means in motor deenergizing condition after its response to initial closure of said safety circuit breaker regardless of the position or" said circuit breaker, means for deenergizing said holding circuit for resetting said safety circuit breaker responsive means for closing the circuit of said driving motors therethrough, and means including a periodically grounded probe arranged adjacent to said carding rolls for measuring the static potential of fibers combed by said carding roll bristles.

References Cited in the file of this patent UNITED STATES PATENTS 2,421,430 Ott June 3, 1947 2,795,012 Gibson et al. June 11, 1957 2,815,483 Kaufman Dec. 3, 1957 

